1.

A statistics professor drew a random sample of 81 observations and found that

x with bar on top equals 20

s equals 12.

Estimate the LCL of the population mean with 90% confidence.

Report your answer to two decimal places.

2.

A major electronics store chain is interested in estimating the average amount its credit card customers spent on their first visit to the chain's new store in the mall. The amount spent on the first visit to the chain store is normally distributed. Fifteen credit card accounts were randomly sampled and analyzed with the following results:= $50.50 and 2 = 400. A 95% confidence interval for the average amount the credit card customers spent on their first visit to the chain's new store in the mall is:

a. 0.50$9.09.

b. $50.50$10.12.

c. $50.50$11.08.

d. None of these answers are correct.

3.

Given that X is a discrete random variable, then the laws of expected value and variance can be applied to show that E(X + 5) = E(X) + 5, and V(X + 5) = V(X) + 25.

True

False